/************************************************************************
 * Copyright (c) 1990, 1993
 *    The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Chris Torek.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 ************************************************************************/




#include "stdio.h"
#include "stdlib.h"
#include "local.h"
#include "errno.h"

#define __SOFF  0x1000      /* set iff _offset is in fact correct */

/*
 * Set one of the three kinds of buffering, optionally including
 * a buffer.
 */
int
setvbuf(FILE * __restrict fp, char * __restrict buf, int mode, size_t size)
{
    int ret, flags;
    size_t iosize;
    int ttyflag;

    /*
     * Verify arguments.  The `int' limit on `size' is due to this
     * particular implementation.  Note, buf and size are ignored
     * when setting _IONBF.
     */
    if (mode != _IONBF)
    {
        if ((mode != _IOFBF && mode != _IOLBF) || (int)size < 0)
        {
            errno = EINVAL;
            return (EOF);
        }
    }
    FLOCKFILE(fp);
    /*
     * Write current buffer, if any.  Discard unread input (including
     * ungetc data), cancel line buffering, and free old buffer if
     * malloc()ed.  We also clear any eof condition, as if this were
     * a seek.
     */
    ret = 0;
    (void)__sflush(fp);
    if (HASUB(fp))
        FREEUB(fp);
    fp->_r = fp->_lbfsize = 0;
    flags = fp->_flags;
    if (flags & __SMBF)
    {
        free((void *)fp->_bf._base);
        fp->_bf._base = (unsigned char *)NULL;
    }
    flags &= ~(__SLBF | __SNBF | __SMBF | __SOPT | __SOFF | __SNPT | __SEOF);

    /* If setting unbuffered mode, skip all the hard work. */
    if (mode == _IONBF)
        goto nbf;

    /*
     * Find optimal I/O size for seek optimization.  This also returns
     * a `tty flag' to suggest that we check isatty(fd), but we do not
     * care since our caller told us how to buffer.
     */
    flags |= __swhatbuf(fp, &iosize, &ttyflag);
    if (size == 0) {
        buf = (char *)NULL;    /* force local allocation */
        size = iosize;
    }

    /* Allocate buffer if needed. */
    if (buf == NULL) {
        if ((buf = (char *)malloc(size)) == NULL) {
            /*
             * Unable to honor user's request.  We will return
             * failure, but try again with file system size.
             */
            ret = EOF;
            if (size != iosize) {
                size = iosize;
                buf = (char *)malloc(size);
            }
        }
        if (buf == NULL) {
        /* No luck; switch to unbuffered I/O. */
nbf: /*lint !e525*/
            fp->_flags = flags | __SNBF;
            fp->_w = 0;
            fp->_bf._base = fp->_p = fp->_nbuf;
            fp->_bf._size = 1;
            FUNLOCKFILE(fp);
            errno = ENOBUFS;
            return (ret);
        }
        flags |= __SMBF;
    }

    /*
    * Kill any seek optimization if the buffer is not the
    * right size.
    *
    * SHOULD WE ALLOW MULTIPLES HERE (i.e., ok iff (size % iosize) == 0)?
    */
    if (size != iosize)
        flags |= __SNPT;

    /*
    * Fix up the FILE fields, and set __cleanup for output flush on
    * exit (since we are buffered in some way).
    */
    if (mode == _IOLBF)
        flags |= __SLBF;
    fp->_flags = flags;
    fp->_bf._base = fp->_p = (unsigned char *)buf;
    fp->_bf._size = size;
    /* fp->_lbfsize is still 0 */
    if (flags & __SWR) {
        /*
        * Begin or continue writing: see __swsetup().  Note
        * that __SNBF is impossible (it was handled earlier).
        */
        if (flags & __SLBF) {
            fp->_w = 0;
            fp->_lbfsize = -fp->_bf._size;
        } else
            fp->_w = size;
    } else {
        /* begin/continue reading, or stay in intermediate state */
        fp->_w = 0;
    }

    FUNLOCKFILE(fp);
    return (ret);
}
